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Tiny probe gives wide-angle view of your insides

By Tom Simonite

A tiny probe could let doctors image the brain from inside out, using ultrasound in several directions at once

(Image: IEEE/Jingkuang Chen)

An ultrasound probe about the size of a grain of rice that could offer panoramic views from inside the human body is being tested by US researchers. They say it could be threaded through blood vessels in the brain or swallowed like a pill.

Ultrasound scanners are normally used to peer into the body from the outside, in order to examine unborn babies or look for tumours, for example.

Enabling these devices to penetrate deep inside the body, and to provide accurate images at this depth, is difficult because longer wavelengths are required, which dramatically reduce resolution.

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Putting an ultrasound scanner inside the body, close to an area of interest, is one solution, and tiny ultrasound probes have already been threaded down veins and into other parts of the body.

But this approach suffers from “tunnel vision” – doctors can only look out in one direction, in front of the probe or to one side. At best, they can rotate the probe to look around.

‘Origami’ structure

The new device – about 1 millimetre across, 1 millimetre long and shaped like a hexagonal cylinder – affords a panoramic picture, showing the view from each side of the device, and to the front.

Jingkuang Chen and colleagues from New Mexico University, Albuquerque, US, and National Taiwan University, Taiwan, created the probe using a novel “origami-style” manufacturing technique.

They first patterned seven components, each capable of emitting ultrasound and listening for the resulting echo, on top of a flat silicon wafer. This silicon was then etched, allowing the wafer to be folded up to form the hexagonal tube.

Stroke prevention

“All the commercially available units can only look to one side or ahead,” says Chen. “We can look out the front and all sides simultaneously.”

The team has completed tests of the device in tanks of water, and plans to test it in animals, attached to the end of a wire-like endoscope.

If these tests prove successful, the hope is that it could offer doctors a much more complete picture of new locations inside the human body. “It could be used to measure blood flow deep inside the brain,” says Chen, “to identify the early stages of strokes or other disease.”